Stereoscopic radiography techniques and apparatus

ABSTRACT

Method and apparatus for stereographic radiography are disclosed, the apparatus including a source of X-rays, a table or cradle disposed beneath the X-ray source, and a cassette disposed beneath the table or cradle, the cassette including a pair of image intensifying screens, a pair of grids between the image intensifying screens, and a double emulsion film between the grids. During the exposure the cradle is moved through an arc while simultaneously creating relative movement between the grids and the film. In the preferred embodiment a shield having a series of slits is disposed between the X-ray source and the patient, with the slits in alignment with the slots in the grids.

[ Jan. 1, 1974 FOREIGN PATENTS OR APPLICATIONS 652,852 5/1951 Great Britain....... 250/61 Primary Examiner-William F. Lindquist Att0rney-Paul J. Sutton [57] ABSTRACT Method and apparatus for stereographic radiography are disclosed, the apparatus including a source of X- rays, a table or cradle disposed beneath the X-ray 6L5 source, and a cassette disposed beneath the table or cradle, the cassette including a pair of image intensifying screens, a pair of grids between the image intensifying screens, and a double emulsion film between the grids. During the exposure the cradle is moved through an arc while simultaneously creating relative movement between the grids and the film. In the fe Int. G0ln 23/04, l-IOlj 37/22 S T N m n g m mT m s e D E n N U STEREOSCOPIC RADIOGRAPI-IY TECHNIQUES AND APPARATUS Inventor: Reuben Hoppenstein, 710 Park Ave.,

New Rochelle, NY. 10021 Filed: June 7, 1971 Appl. No.: 150,297

Field of Search.......................

United States Patent Hoppenstein prerred embodiment a shield having a series of slits is disposed between the X- ray source and the patient, with the slits in alignment with the slots in the grids.

10 Claims, 8 Drawing Figures Goffc et al... Arfstcnt..l..i....t...,.... Tokuyama et Bonnet.............

STEREOSCOPIC RADIOGRAPHY TECHNIQUES AND APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to radiography or roentgenography, and specifically concerns novel tech niques and apparatus for producing radiographs which create an illusion of depth to the viewer and thereby provide images possessing stereoscopic or threedimensional characteristics.

2. Description of the Prior Art The production of a standard radiograph or so-called X-ray is a relatively simple technique requiring merely the generation and transmission of a burst of electromagnetic radiation to and through a target or subject, the radiation burst thereafter impinging upon and exposinga fixed film record. Shadow images and the like are produced on the film record in dependence upon and in direct relation to various characteristics of the subject or target through which the radiation was transmitted. The film record or image so produced is, of course, two-dimensional, much like a standard photograph.

In many investigative applications, however, both in the medical and other environments, these standard two-dimensional or planar radiography techniques are not entirely satisfactory. For example, when a radiograph is desired of a human subject and particularly of those body areas within the subject having bony densities adjacent soft tissue, the bony densities have been found to actually obscure the less intense shadows of the soft tissue and thus degradethe resultant film record and inhibit medical analysis. Furthermore, when utilizing standard radiography techniques, for a precise location and study of body tumors, for example, a multiplicity of conventional radiographs are oftentimes required to be taken fromya number of different positions and diverse angles.

In view of the inherent disadvantages and limitations of two-dimensional or planar roentgenography, the medical radiographer has looked to other X-ray techniques in an attempt to improve the quality, accuracy, versatility and usability of the X-ray film image. Specifically, many attempts have been made in an effortto develop three-dimensional radiography techniques, the more successful of these prior stereographic techniques ultimately generating a film or viewing record exhibiting the characteristic and illusion of depth to the perceiver. These efforts have proven stereoscopic radiography to be of particular medical value since, at least in theory, all film shadows can be reduced into their components in a three-dimensional space to thus give a more accurate picture of density. Furthermore, hairline fractures and other fine details can be revealed more clearly with the stereoscopic image. The soft tissue areas adjacent bony densities can be viewed with greater facility and all definitive points of interest to be examined within the subject can more accurately be located.

While the general concept of stereographic radiography is not new, adequate and commercially usable techniques and apparatus for the production of such stereoscopic records have yet to be fully developed. For example, many prior art approaches in this area relied for their effectiveness or operability upon doubleimage techniques using stereographic pairs. The stereographic pairs, when viewed from some particular viewing position created visual parallax or an illusion of depth. An inherent limitation of this basic technique resided in its limited area of viewability, and further limitations resided in the complexity and general unwieldy nature of the equipment necessary in the process. As the art progressed, different though still somewhat unsophisticated techniques were developed which not only provided a film record containing parallax, but also provided the possibility of viewing the film record from virtually any position. These techniques required the use of lenticulated images and the concurrent utilization of the so-called lenticular viewing lens. It is from this state of the art that the instant invention has sprung.

The principles upon which this invention is based are closely related to those of the optical sciences and perhaps a discussion of the optical theoryof parallax, spatial illusion, and three-dimensional viewing would be appropriate so as to facilitate a better understanding of the invention.

As is known, three-dimensional or stereoscopic photographs of an object can be made by exposing a photo graphic film record in a suitable manner such as through a lenticular screen with attendant relative movement between the camera lens, the object, and/or the film. When the resulting photograph is then viewed through a lenticular screen having suitable optical characteristics, the picture seen will create an illusion of depth and specifically will appear to have threedimensional or stereoscopic characteristics, regardless of the viewing angle.

As an example, attention is herein initially directed to FIG. 1 which is representative of one standard optical technique of producing a photograph having threedimensional viewing characteristics. As is well-known, in order to create a true three-dimensional viewing effect in accordance with currently accepted principles, it is necessary to view the exposed base film image through a lenticular screen and to provide a lenticulated or strip-like base image on the photograph itself, each strip-like image being representative of a different viewing angle of the object being photographed. Thus, standard techniques dictate the utilization of a lineated screen in the camera itself so as to provide parallax.

DESCRIPTION OF THE DRAWINGS The invention itself, as well as additional advantages and features thereof, will be more readily and comprehensively understood from the following detailed description of the preferred inventive embodiments, such description making reference to the appended sheets of drawings, wherein:

FIG. 1 is a schematic illustration of a prior art optical technique for obtaining a film record containing parallax and providing a visual depth effect, as already discussed; v

FIG. 2 is a schematic illustration of a film containing a plurality of discrete images providing depth informa tion, and an overlying lenticular screen so as to enable observation of the film record from virtually any angle, as above-discussed;

FIG. 3 is a schematic illustration of the basic inventive system for purposes of facilitating an understanding of conceptual system operation;

FIG. 4 is a perspective illustration of one embodiment of the overall invention providing a system capable of producing three-dimensional radiographs or X- rays;

FIG. 5 is a schematic illustration, partially broken away for illustrative clarity, depicting one embodiment of the novel X-ray film cassette of the instant invention;

FIG. 6 is a perspective illustration of another embodiment of one component part, i.e., the grid or screen, contained within the novel cassette of FIG. 4;

' FIG. 7 is an electrical schematic diagram of one form of suitable control and synchronizing means for the various components of the overall system as illustrated in FIG. 3; and

FIG. 8 is a diagramatic illustration of one preferred technique for producing the screen or grid of FIG. 5 for utilization within the novel cassette of FIG. 4.

Typical prior art cameras for obtaining such threedimensional photographs are well-known and are schematically indicated in FIG. 1 and will be seen to generally comprise a standard commercial camera 10 mounted on a suitable non-illustrated structure for traversing a path about a plurality of target objects 12, 14 and 16, the camera carrying-film 11 at the rear of the camera housing, and an overlying lenticular screen 13. As shown in FIG. 1, the camera therein provided is capable of being moved between dotted-line positions along an arc whose radii intersect at the point 18, the central point of any particular picture to be taken. The target or object itself is shown as comprising a triangle 12, a circle 14, and a block 16, disposed in different lateral positions relative to the center of the traversing arc upon which the camera 10 will travel and at different distances from the arc path itself. The camera 10 can be assumed to be moveable from an initial position as shown in dotted-lines, and the left, through a central position as shown in solid lines, and to a final position shown in dotted-lines on the right.

The different relative positions of the camera while photographing the object, or the difference in point of view, i.e., parallax, of the camera as it traverses its arc is illustrated by the rays extending from each of the cameras. The relative rays are designated by dotted lines with respect to the left position of the camera, by solid lines with respect tothe central position of the camera, and by dash lines with respect to the right position of the camera. It should therefore be noted that with this arrangement, the camera 10 will view the objects l2, l4 and 16 from different points of view as the camera traverses its arcuate path.

As mentioned above, a lineated screen 13 of any suitable form is incorporated in the traversing camera 10 between the camera lens and the film 11 and this lineated screen must be sequentially moved along with movement of the camera 10 between the two end points of its path of travel. By virtue of the refractive and focusing characteristics of the lenticle elements of a conventional lenticular screen, light received by the camera lens and passing to the screen will be focused onto a given vertical line of the film behind each lenticle and, as the screen moves, this vertical line also moves so as to produce the lenticulated image on the film the developed film being illustrated at 20 in FIG. 2. What will be stored, then, on the camera film, is a plurality of lenticulated images or strips of the objects 12, 14 and 16, each viewed from a difierent angle and thus containing what can be termed parallax.

The image so produced on the film though comprising a plurality of individual lines, is continuous within a given film area disposed beneath a single lenticle of the overlying screen, although the point of view from which a given object is seen varies within the panel across the width thereof. Referring now to FIG. 2, a typical conventional lenticulated image as is produced by developing the film is shown and will be seen to comprise the underlying exposed film 20 and a superimposed plurality of lenticles forming a screen 22, similar to screen 11. As stated above, beneath each one of the lenticles of the screen 22, a complete and continuous image of the objects 12, 14 and 16 will be found, in a plurality of separate line exposures. When the underlying film or base layer 20 is disposed beneath a lenticular screen 22 with the individual lenticles of the screen being disposed in overlying alignment to the individual panels or strips of the film then a person viewing the unti will see a three-dimensional picture or, more specifically, a picture creating an illusion of depth.

As shown in FIG. 2, and assuming points 24 and 26 to be the left and right eyes, respectively, of a viewer,

the users right eye 36 would see rays reflected along I the lines 28 and 30 and the users left eye 24 would receive rays reflected, for example, along the lines 32 and 34. The rays 28 and 30 emanate from, or technically are reflected from a point in one panel or strip of the underlying film which is spaced laterally of a point in the same panel from which rays 32 and 34 are reflected to the users other eye. The effect is as if the viewer was using a stereoscopic slide disposed within a stereoscope. Separate images of the same picture differing in point of view are received simultaneously by the respective eyes of the viewer, and the viewers brain will merge such images and create, through sensory perception, the three-dimensional illusion. While the unit of FIG. 2 has been described with respect to what occurs behind a single lenticle of the lenticular screen 22, it should be understood that the viewer would see many lenticles simultaneously by virtue of the relatively small size therof and thus, the viewer would receive an overall picture in three-dimensions. The operation with respect to each of the lenticles is the same as that described and thus, the illusion created by each lenticle need not be discussed in exhaustive detail.

As will be recognized, formation of the lineated images on the film record 11 in the camera 10 can be achieved in a number of different conceptual ways. As described, the lineated images were obtained in the representative embodiment of FIG. 1 by placing a lenticular screen behind the camera lens in a superposition with respect to the underlying film and then moving or traversing the camera along an arcuate path, while simultaneously moving the screen. In order to obtain a complete or continuous image behind each lenticle of the screen, the amount of advancement would necessarily have to be equal to the width of one such lenticle. Rather than traversing or moving the camera and, simultaneously therewith, the screen, the film might be moved, or the camera could remain stationary, and the film and the various targets 12, 14 and 16, could be si multaneously moved. As should be apparent, all that is required is relative movement between the camera, the film and the objects to be photographed so that parallax will be created by the mechanism of obtaining a film record of the targets viewed from different positions thereof.

a photographic film record is obtained of the light emanating or reflected from the targets to be photographed, this light then passing into the camera through a lenticular screen and onto underlying film. With X- rays, on the other hand, reflected" light is not utilized and, instead, ray energy-is generated which passes completely through, or at least substantially completely through, the object to be photographed. Further, the utilization of lenses and thelike as discussed would have'substantially no effect on X-rays and such lenses cannot be. directly introduced into an X-ray system. Thus, here too, a marked departure from the prior art optical stereoscopic techniques is indicated.

Bearing in mind the foregoing discussion, it is a primary object of the instant invention to provide a stereoscopic or three-dimensional radiographic or X-ray technique and apparatus which produces a radiograph offering the viewer thereof an illusion of depth, as is the case with optical systems.

It is a further object of the instant invention to provide stereoscopic techniques and apparatus for radiographs .by which the resulting image clearly distinguishes between shadow areas and by which the relative depth of objects visible in said resulting image can readily be ascertained.

It is a further object of the instant invention to produce what may be termed time-sequential radiographs on a single X-ray film, utilizing the three-dimensional stereoscopic techniques as above-mentioned, so as to 7 provide a time record of events on X-ray film.

Yet another object of the instant invention concerns the provision of a fully three-dimensional radiograph which can be viewed from any angle without the need for unwieldy equipment. I i

A still further object of the instant invention is to provide a stereoscopic or three-dimensional radiograph plate wherein resolution between various body tissues is greatly facilitated thus facilitating medical analysis and diagnosis.

Yet another object of the instant invention concerns the provision of three-dimensional films having socalled look-around ability in contrast to stereoscopic pairs of X-rays which do not have this capability.

Another advantage and object of the instant invention concerns the provision of a radiograph which separates and assists in the identification of different densities of the body which, at present, are superimposed on standard X-ray films.

Another object of theinstant invention concerns the provision of a three-dimensional radiograph wherein spatial relationships become obvious as do positions of foreign bodies.

Yet another object of the instant invention concerns the provision of a radiograph by which an entire dynamic study can be recorded, such as would be necessary in the medical processes of angiography, angiocardiography, nephroangiography, intravenous pyelography, barium swallows, and the like, on a single sheet of film.

Another object of the instant invention concerns the provision of a three-dimensional radiographic technique and apparatus so as to provide a unique teaching medium for the medical studentor resident.

Stil another object of the instant invention is to pro vide such a three-dimensional radiographic technique wherein standard X-ray generators, tubes, film and processing equipment can be utilized, thus greatly reducing the cost of the system.

c A further object of the instant invention concerns the provision of a system providing three-dimensional X- rays, which system is also capable of producing standard two-dimensional X-rays as desired.

A further object of the instant invention concerns the provision of a system capable of taking complete X- rays of a patient, such as in laminography, wherein total radiation to the patient is still considerably'reduced.

Another object of the instant invention concerns the provision of a system which possesses economic advantages over prior'art systems since fewer sheets of film are needed and since shorter development time and more compact facilities are necessary.

These objects as well as other objects which will become apparent as the description proceeds are implemented by the instant invention which, as aforestated, relies upon the basic principles of optical threedimensional stereotography, adapted for utilization in i an X-ray radiograph system.

SUMMARY OF I THE INVENTION Briefly described the novel invention contemplates the utilization of a standard and conventional X-ray source as the source of radiant energy, this generator generating a burst of X-rays for passage through a tar get or patient and for subsequent impingement upon an X-ray film record disposed beneath the patient. The patient himself, in apreferredinventive embodiment, is placed upon a cradle or other moveable X-ray table which, during the instant process, is adapted to move through an arcuate path thus presenting different positions and angles of the patient to the incoming ray en ergy. In the preferred embodiment, the film record disposed beneath the patient is contained within a novel cassette, the cassette containing a novel screen or gridlike arrangement disposed in a position above or adjacent the. film this grid-like arrangement performing in a different'manner the function for X-rays that the len- V ticular lens in the camera as initially-discussed performed in optical systems. During exposure, the source of ray energy is fixed in position, the patient on the era tile or X-ray table is moved and, simultaneously and synchronously with such patient movement, either the film in the cassette or the superimposed grid-like arrangement is likewise moved. As a result, a plurality of lineated images are obtained on the underlying X-ray film,which images can be viewed to present an illusion of depth or a three-dimensional effect through the use of a conventional lenticular' optical screen.

Of course, it should be kept in mind that it is not necessary to rotate or move the patient on the cradle synchronously with the cassette mechanism or film while retaining the existing X-ray tube and generator in a stationary position. From a theoretical point of'view, there appears to be three techniques or methods by which the radiographs can be created. For example, the X-ray tube and the cassette, the tube and the patient, or the patient and the cassette could move in synchronous unison. Yet, advantages are obtained by utilizing the preferred technique since existing X-ray tube generators and structure can be retained.

The cassette contemplated for utilization will also be seen to include novel structure specifically designed to reduce the total radiation time of the patient to thus greatly increase the safety of the technique. For example, the X-ray film utilized is preferably coated on both sides, both the side nearest to the impinging X-rays and the side furthest away. On each side of the film a medium for producing secondary emission, such as a phosphor coated intensification screen is in superimposed relationship to the film and, on each side of the film, between the film and the intensification screen, the above-discussed grid-like screen arrangement is provided. Accordingly, X-rays impinging upon the underlying film will expose the film through both primary and secondary emission techniques as will be discussed in more detail in the body of the specification. As stated, a mechanism is provided for effecting relative movement between the film and the screen synchronously with the patient movement.

The resultant product obtained, that is the exposed X-ray film now containing a plurality of continuous laminographic images, each image composed ofa number of lenticulated lines representing different angles of view of the target, can be viewed through the utilization ofa lenticular viewing screen as above-discussed. In the preferred embodiment, the lenticular screen is placed in superimposed relationship over the film and the lenticular screen contemplated for utilization will be seen to preferablycomprise a series of cylindrical lenses, each 0.4 millimeter wide and running the length of the film over which it is placed. With a standard 8 inch by 10 inch radiographic film, 500 separate lenticles will be seen to cover the narrow dimension or 850 separate lenticles could be utilized over a 14 inch by 14 inch plate. And, in accordance with the optical principles above-discussed, and considering the utilization of a lO-exposure film,for example, each lenticle will be seen to reduce the image that strikes it to a narrow strip 0.04 millimeter wide.

During exposure with the novel system, and in the preferred embodiment, the film itself is moved 0.04 millimeter in a direction opposite to that of the patient, which patient is, as above-discussed, being rotated in the special cradle. This brings a new 004 millimeter wide strip into focus to receive the second image, while the rotation of the patient provides a new viewpoint for this image. After 10 images are exposed, for example, and the patient has been rotated through an angle of from about 8 to about 20, preferably from 8 to 15",

although for a thick laminogram an arc of 15 to is employed, the film is removed from the cassette and developed. Now, to view the film, the observer places it behind a lenticular screen as above-discussed and, with his right eye, sees one of the 10 strips behind each lenticle magnified so that the images cover the entire film. With his left eye, the observer sees another set of strips, this set from another exposure angle. Thus, parallax is seen, as discussed with respect to the optical system, and so, an illusion of depth is created. As the resulting film is rotated, different sets of strips come into view and thus, a look around" capacity is created of the object recorded on the film.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, attention is initially directed to FIG. 3 thereof where the overall system operation can briefly and conceptually be explained. The instant inventive system, as aforestated, contemplates the utilization of any existing, .standard and conventional X-ray source such as depicted by reference numeral 36 to provide the souce of radiant or X-ray energy. Such conventional equipment is any standard X-ray generator of the 300 MA to 1000 MA class coupled to any standard X-ray tube having a focal spot size of 1 millimeter or less. The 0.3 millimeter spot size is used for magnification studies. The radiation emitted fom the conventional X-ray source 36 is directed toward and-passes through a target, represented by a patient 38 disposed upon a cradle 40 or moveable table, the cradle being adapted to move through an arcuate path such as represented by arrow 42 to thus present different positions and angles of the patient to the incoming ray energy. The cradle or table top is devised to traverse an arc of 30 i.e., 15 in each direction from the rest position, in a given period of time, e.g. 10 in one second or 15 over 8 seconds. As aforementioned, usually an arc of 8 to 15 is employed for best results, although an arc of 20 to 30 is used for thick laminograms.

A film record is disposed beneath the cradle or table 40 carrying the patient 38, this film record being contained within a novel cassette generally designated by reference numeral 44, the cassette containing a novel screen or grid-like arrangement disposed in a position above or adjacent a layer of film. As discussed, this grid-like screen or arrangement performs, in a different manner, the function for X-rays that the lenticular lens in the camera of FIG. 1 performs in an optical system.

The cradle or table 40 is'contemplated to be motorized as are the component portions of the cassette 44, relative motion between the film and the screen or gridlike arrangement in the cassette being in the direction of arrow 46 and opposite to the direction of rotation of the cradle or table 40. As will be discussed by reference to other figures of the appended drawings, automatic and synchronous operation is contemplated by the instant invention so that a selected and preferred amount of relative movement between the film and the screen or gird-like arrangement takes place and so that the table or cradle 40 moves synchronously with the film and grid-like arrangement and through a preferred angle of rotation.

With the overall system, the particular angle of rotation of the cradle or table 40 can be varied depending upon the site of major interest within the target or patient 38. A greater angle of rotation, i.e., 20, will result in a narrow field of sharp focus producing a greater three-dimensional illusion on the film within the eassette 44. A ten degree rotation of the cradle or table 40, for example, would result in a large field of sharp focus and would diminish the three-dimensional or depth perception effect. The cradle or table 40 can also be raised or lowered to change the particular axis of its rotation and thereby the level of the field of sharp focus would also be varied as will be discussed in detail hereinbelow.

During operation, the X-ray tube or generator 36 is energized and synchronous though opposite movement is effected between the cradle or table 40 and the un derlying components within the film cassette 44. In this fashion, a plurality of distinctive and different X-ray views can be exposed on the film within the cassette 44,

each view being changed from the other due to the rotation of the target or subject 38 on the cradle or table 40. The thus exposed film within the cassette 44 is then developed and can be observed through a special viewer such as that already described with respect to the prior art and illustrated in FIG. 2.

Specifically, a lenticular screen is contemplated to be placed immediately above the exposed film, such as screen 22 relative to film in FIG. 2. By viewing the exposed and developed filmthrough such a lenticular screen, an illusion of depth will be seen by the viewer as to the composite picture in the fashion discussed with respect to the optical'techniques above.

During the following discussion of the actual preferred inventive embodiments, it should be noted that, from a conceptual point of view, the Xray source and the cassette, the source and the patient, or the patient and the cassette, respectively, mustmove in synchronous unison though, with the instant preferred invention, the patient is rotated on a cradle moving synchronously with the film cassette so as to enable the retention of existing X-ray tube and generator structure and thus offer an advantage of economy.

Furthermore, it should be kept in mind that many dif-' ferent viewing techniques have been and can be devised for observing the developed X-ray film. For example, by placing a lenticular screen over the film and by thereafter moving the lenticular screen relative to the film,a short three-dimensional dynamic movie sequence results. Specifically, if an angiogram is recorded, when viewed in the above-described manner, the contrast media will be seen to flow through the vasculature in a three-dimensional manner. The same angiogram can be viewed as a two-dimensional study, or as individual sequences as desired.

Furthermore, it should be noted that if the relative motion between the cassette components and the table or cradle is not effected in an opposite manner, but is effected in the samedirection, a so-called reverse image results which may have value with respect to medical diagnoses.

Referring now to FIG. 4 of the drawings, a preferred overall structural embodiment of the instant invention is'shown. Like parts within this preferred system have the same reference numerals as that discussed with respect to FIG. 3. 1

Thus, it will be seen that a standard X-ray source 36 is preferably disposed upon a stand 48 for vertical adjustment by an interlocking collar 50. The X-ray source 36 is disposed on a frame member 52 which is slotted such as at 54, an extending rod 56 extending outwardly from the casing of the standard X-ray source 36 for sliding movement within the slot 54 so as to effect horizontal adjustment. For use with the invention, virtually any standard existing X-ray source structure and support so as to effect conventional vertical and lateral movement can be utilized if desired. Once the X-ray source 36 is properly disposed in position, further movement is not necessary as all subsequent focusing adjustments and the like can be effected through displacement of the remainder of the system components relative to the fixed X ray source 36.

In FIG. 4, the rotatable table or cradle 40 and the subject or target 38 thereon, illustrated by the dotted lines, are disposed between the X-ray source 36 and the underlying film cassette 44. The rotatable table 40 can be of any suitable construction which offers the various degrees of movement to be discussed. Specifically, and in the preferred inventive embodiment, the rotatable table 40 is contemplated to include an extending shaft 58 which is fixedly mounted to a block 59 which is slideably mounted to the rotatable table 40 at a sidewall 60 thereof through a motor driven screw arrangement 61. The shaft 58 is journalled for rotation within I a carrier or stanchion generally designated by reference numeral 62, this carrier or stanchion itself being adapted to be adjusted up and down as indicated by direction of arrow 64 by virtue of a hydraulic cylinder as sembly, generally designated 66, of conventional construction. This allows for adjustment of the distance be tween the X-ray source and the patient. In order to align the center of interest to the-physician with the rotational axis, the table is lowered or raised relative to the block 59 which is then locked in position.

An electric motor 68 is disposed on the carrier or stanchion 62, the motor including a shaft having a gear 70 thereon which is connected, via a chain or other suitable mechanical connection 72., to a cog or gear 74 disposed on the end of the shaft 58. In this fashion, when motor 68 is energized, the rotation of the motor shaft serves, through the illustrated gearing, to effect rotation of the shaft 58 extending from the rotatable table 40 and thus serves to move the rotatable table 40 through an arcuate path such as represented by'the arrow 42. The actual position with respect to angular rotation of the cradle or table 40 is sensed by a sensing mechanism 76 which is schematically illustrated in FIG. 4 and will be discussed in more detail hereinbelow. 1

The cradle or table 40, in addition to being adjustably mounted both in the vertical and in the angular or rotational directions, is also capable of effecting lateral and horizontal movement in the direction of arrows 78 and 80, respectively, by meansof any suitable structure such as that schematically illustrated at 82.

Disposed beneath the rotatable table or cradle 40 is the film cassette 44 which, in FIG. 4, is shown partially sifying screens andan additional screen or grid-like arrangement similar to that illustrated as at 84. Relative movement is effected between the illustrated or gridlike arrangement 84 and the underlying film 86 in the direction of arrow 46 by means of an electric motor arrangement 88 and the actual position of the screen or grid 84 relative to the film 86 is sensed by a sensing mechanism 90 as schematically illustrated, this mechanism being similar to mechanism 76 discussed with respect to the rotatable table or cradle 40.

The screen or grid 84 which, in this embodiment will be assumed to be the driven member effecting the relative movement between the screen and the film, contains a plurality of slits 92 in the form of a grid. In the absence of an image intensifying screen as will be discussed hereinbelow, the grid-like arrangement 84 could be substantially impervious to the incoming rayenergy except for that portion of the screen or grid-like arrangement 84 defined by the slits 92. As the screen or grid 84 moves, the various portions of the underlying film record 86 would be exposed, the incoming energy providing a plurality of discrete line images. Since, at the same time, the subject 38 is rotating by means of the rotatable motor-driven cradle or table 40, each of the discrete line images or views disposed on the film record 86 would contain information representative of a different angle of view of the target or patient 38. The composite picture, when developed and viewed through a lenticular screen such as that discussed with respect to FIG. 2, would present an illusion of depth by virtue of the parallax recorded thereon.

During the course of the exposure by the X-ray source 36, very little of the ray energy itself is utilized for purposes of effecting exposure of the film record 86. Most of the ray energy, at least so far as its effect on the film record is concerned, is lost due to the action of the screen or grid-like arrangement 84. Yet, when using a diagnostic technique requiring multiple bursts of radiation, if the .total amount of this ray energy impinged directly upon the patient or target 38, an overdose of radiation might result.

It is for this purpose that, in the most preferred embodiment, a second screen or grid-like arrangement generally designated by reference numeral 94 is provided, this element, in fact, comprising a shield preferably made of lead or like material impervious to incoming radiation. The shield 94 includes a plurality of slits or slots 96 in registration with the slits 92 in the screen or grid-like arrangment 84 within the film cassette 44. During operation, movement of the shield 94 is effected in the same direction (see arrow 98) as the direction of movement of the grid 84 within the cassette 44 and, accordingly, only that amount of the incoming radiation that passes through the slots 96 is allowed to impinge upon and pass through the patient 38, the transmission path of this radiation being, as abovementioned, in registry with the grid 84 of the cassette.

The motion of the shield 94 in the direction of arrow 98 is achieved through the utilization of an electric mechanism incorporating a motor 100 having a gear 102. Gear 102 meshes with a saw-tooth like gearing arrangement 104 disposed at one end of the shield 94.

The shield 94 is itself disposed within a slot 106 of a frame 108, the frame being attached by a collar 110 to the upstanding shaft 48. In this manner, the position of the shield 94 with respect to the X-ray source 36 and with respect to the underlying film cassette 44 can be adjusted as desired so as to insure registration as discussed. A sensing mechanism 112 is provided on the frame of 108 so as to sense the actual position of the shield 94 in a similar fashion to sensors 76 and as the slots 92 of the grid 84 in the cassette 44, the angle of these slots 96 through the shield 94 is made such as to account for the normal spray of radiation coming from the X-ray source 36 and the resulting divergence of the radiation. So as to account for such divergence and spray, the relative position of the X-ray source 36 and the shield 94 must be fixed and a predetermined distance between the shield 94 and the X-ray source 36 must be maintained.

Having the general disposition of the individual components of the overall system now firmly in mind, attention is now directed to FIG. 5 depicting a schematic illustration of a preferred embodiment of the film cassette 44. A novel film cassette 44 is contemplated to utilize conventional X-ray film 114 in the illustrated sandwich having a double emulsion-i.e., an emulsion layer disposed on either side of the film. This particular construction allows the ultimate reduction, as will be discussed, of one half of the radiation necessary to achieve a proper exposure. Disposed immediately above the film 114 is the screen or grid-like arrangement 84 as above-discussed having a plurality of effective slots 92 therein. The screen or grid 84 could, if desired, be constructed of a metallic foil-like material, preferably of a heavy metal such as gold, silver, platinum or lead, with a plurality of slots 92 being etched therein. The disposition and spacing of the plurality of slots 92 is predetermined and, as an example, 850 slots could be provided over the film surface, using a 14 inch by 14 inch plate, each slot having a width of 0.04

millimeter, corresponding to a lenticle pitch of 0.4 millimeter, the grid or screen-like arrangement 84 being adapted to be moved, during exposure, 0.04 millimeter over the predetermined period of time of one second while the cradle 40 moves through 8 to 15.

An image intensifying screen or sheet 1 16 is disposed immediately above the grid-like arrangement 84, this image intensifying screen being constructed of fluorescent materials, for example, such that when the incom ing radiation burst impinges thereon, secondary emission of photons will be effected. These photons then pass through the slots 92 in the screen or grid 84 to thus expose the sandwiched X-ray film. If desired, and in one alternative embodiment, the screen or grid 84 could comprise metal deposited on the underlying surface of the intensifying screen 116 and th4 slits or slots 92 thereafter etched therein. The particular thickness of the deposited metal layer is not critical though it is preferable that such metal layer be thick enough to shield the direct radiation from the film, yet thin enough so as to minimize distortion of sharpness. In any event, only a small amount of radiation would actually strike the photographic material itself in any case.

A second image intensifying layer 118 is disposed on the opposite side of the film cassette 44 and, between the second intensifying screen 118 and 'the film 114, a second screen or grid-like arrangement 120 is provided, identical in construction to grid 84 so that the various slots therein are in absolute alignment with one another. By so utilizing a second image intensifying layer 118 and underlying screen 120, the incident X-ray radiation which passes through the film 114 strikes the underlying image intensifying layer 118 and is reflected back to the film to expose the second emulsion thereof. As should be appreciated, the total radiation dose necessary to effect a proper radiograph under these circumstances is markedly reduced thus, again, protecting the patientfrom an overdose of radiation.

Of course, with the utilization of a double grid sandwich arrangement, both of the screens or grids 84 and 120 must be moved in absolute synchronism with respect to one another. 'Such, synchronous motion is achieved by actually mechanically coupling the two screens together in the preferred inventive embodi ment such as illustrated by the structure generally designated by reference numeral 122, which structure is merely exemplary of that which may be used to effect this function. In a fashion similar to that discussed with respect to the shield 94 in- FIG. 4, a saw'tooth like gearing arrangement 124 is included with the interconnecting structure 122, this gearing arrangement 124 being driven by a pinion gear 126 coupled to the electric motor 88 as above-described. The function of sensing the actual location of the screen or grid-like arrangements 84 and 120 with respect to the film 114 sandwiched therebetween is, as aforestated, effected by the sensor generally designated by reference numeral 90 which, in one embodiment of the instant invention, comprises arheostat or: variable resistor having a wiper arm 128 coupled to the saw-tooth gearing 124, and an associated fixed resistor 130.

Attention is now directed to FIG. 6 where a further preferred embodiment of construction of the screen or grid-like arrangement'84 or 120 is disclosed. Rather than utilizing a metal deposited layer, or foil and subsequent etching, a plurality of grid lines and the like can be achieved through a photographic process. Specifically, and as contemplated by the instant invention, the

' screen or grid-like arrangement will be seen to comprise a layer of photographic film 132 having a plurality of darkened or exposed portions 134 thus effecting an equivalent of the slits or slots 92 of the grid-like arrangement 84 depicted in FIG. 5. The utilization of such a photographic or film grid or screen is preferred due to its relative simplicity of manufacture and, per haps more importantly, the precise accuracy in which thevarious grid lines can be obtained. In this respect, one preferred technique by which the screen of FIG. 6 can be obtained is depicted in FIG. 7 and attention is therein directed.

A point source of light 136 isdisposed to one side of a slotted or slit diaphragm 138. To the other side of diaphragm 138, a photographic film sheet 140 is provided having an overlying layer of lenticular screen material 142 such as discussed with respect to FIG. 2 hereinabove. The Ienticles have a pitch p of, for example, 0.4 millimeter. During exposure of the photographic film 140 by the point sourceof light 136, the film and the overlying lenticular screen layer is rotated abouta central axis in alignment with the point source of light 136 and the slot 144 of the diaphragm 138, in the direction of arrow 146. The point source of light would be periodically energized during this operation and, as a result of the refraction of the lenticular lens or screen 142, a plurality of discrete line images will be exposed on the film 140. The particular width and spacing of these line images can be precisely controlled by controlling the rate and amount of rotation of the film 140 about its central axis and by controlling the duration and period of the periodic energization of the point source of light 136. The resulting film record .140 would thereafter be developed and provide the screen illustrated in FIG. 6 above-discussed.

. chronism. Alternatively, more sophisticated and elec- Throughout the instant discussion, reference has been made to the importance of synchronization of the relative movement of the shield 94, for example, along with the rotatable cradlegor table 40 and the screen or grid 84 and 120 within the film cassette 44. Any suit able synchronization means could be utilized to achieve this function. For example, a single drive means could be provided and each of the various elements above-discussed could be mechanically interconnected, one to the other, so that movement of one with respect to the other is rigidly maintained in syntronic techniques could be utilized if so desired and one preferred embodiment. of such an electronic technique is illustrated herein. Attention is now directed to FIG. 8 of the drawings.

One suitable, though exemplary, synchronization means for theinstant invention is depicted in FIG. 8 and forms the energizing or controlled power source for the various motors as above-discussed such as the shield motor 100, the table or cradle motor 68, and the screen or grid motor 88. In control and timing computer means 148 is provided having outputs directly coupled to the various motors 100, 68 and 88 so as to energize same and effect their rotation. Of course, the particular gear ratiosv between the motors and the drivenelements themselves such as the shield 94 and the like have been carefully preselected. Once a start command has been enteredinto the control unit 148, each of the motors 100, 68' and 88 would be energized.

Although, as aforestated, the gearing arrangements themselves should effectthe synchronization between movement of the elements,'it is preferred to provide an additional feedback control mechanism serving to actually sense the position of the various elements, and feed back this sensed position into the control means 148 so as to correct the amount and duration of energization of individual motors. It is for this purpose that the various sensors 112, 76 and 90 associated with the motors and the driven elements have been provided. The output of the various sensors provides direct indication of actual position and serves to override the inherent operation 'of the motors with their associated gearings if necessary so as to insure synchronization. After one particular exposure, each of the motors is stopped and, by application of a reset signal into the control unit 148, the various motors are reversed to bring the system back into la read;y" condition for the subsequent start of a new exposure.

Referring again to FIG. 4, an exemplary period of system operation will be described. The patient or other target 38 is placed in position on the rotatable cradle or table 40. The X-ray source 36, the shield 94, the table 40, and the underlying film cassette 44 are aligned. A start signal is then introduced into the control unit 148 of FIG. 8 and the shield motor 100, the table motor 68 and the grid motor 88 are all energized. Likewise, the X-ray source 36 is energized and radiation is emitted therefrom.

The shield 94 and the screen or grid-like arrangement 84 and within the film cassette 44 are, therefore, moved, in the preferred embodiment, in the direction of arrows 98 and 46, respectively. At the same time, the patient 38 upon the cradle or table 40 is rotated in an arcuate path in the direction of arrow 42 and, in this manner, presents different angles to the incoming radiation from the X-ray tube 36. Absolute synchronism of the relative movement as above-described is effected by the control unit 148 in cooperation with the output of sensors 112, 76 and 90.

As a result, a plurality of line or strip images, each depicting a portion of the subject from a different point of view, are recorded on the film 114 within the eassette 44. Following exposure, the film 114 is developed in ordinary fashion and is placed beneath a lenticular screen such as is indicated in FIG. 2. This film, when viewed through the lenticular screen, creates an illusion of depth perception and thus greatly facilitates diagnoses and medical techniques as described at the outset of this specification.

It will be appreciated by those skilled in the art that various modifications in operational technique as well as in structure could be made to the preferred system above-described, some of which modifications are discussed hereinbelow.

Although an example has been given for a study using pictures, so that the screen or grid-like arrangement moves 0.4 millimeter over a time period of, say one second, while the cradle moves through an arc of 8 to in one second thereby making 10 pictures, each 0.04 millimeter wide, this is not to be construed as the only possible relationship. In fact, up to 24 series of pictures can be made on one sheet of film using the present technique and equipment, over any preselected time period, the width of each strip then being 0.4/n millimeter, where n is any integer up to 24.

Furthermore, another preferred embodiment utilizes movement of the film l 14 instead of the screen or gridlike arrangements 84 and 120 as indicated by dotted 7 lines at 150 in FIG. 5.

EXAMPLES I. A dry skull with simulated arterial tree constructed of wires of differing diameters from 0.5 millimeter to 2 millimeters, was radiographed in different planes with varied axis and angles of rotation.

These studies'demonstrat ed that even the most inexperienced observer could'accurately localize the exact relationships of each wire. The magnitude of the apparent three-dimensional depth was directly proportionate to the angle of rotation through which the skull was made to rotate. While a larger angle'produced greater three-dimensional preception, but a narrower field of sharpfocus, the converse held true for smaller angles of rotation. With an angle of rotation of 15 the apparent depth was approximately 5 inches.

True antero-posterior views were recorded when the subject was rotated in a'clockwise direction. Counterclockwise rotation resulted in a pseudo posteroanterior view, as if viewing the subject from behind. This is due to the fact that it leads to the deposition of the laminograms in the reverse order.

On lateral three-dimensional studies the simulated anterior cerebral artery remained in the same plane moving forwards or backwards only. The middle cerebral artery complex on the other hand moved away at an angle on the same maneuver. Provided the axis of rotation is through the true mid-line, all structures in that plane will only'move to theright or left on movement of the observer's head.

The information derived from a single film contained fundamentally the data that could be distinguished on at least three 'or four separate radiographs, For example, on an A-P of the skull, the optic foramina, the interal occustic meati and all the sinuses could be plainly distinguished. A standard A-P of the skull would not present this information because of superimposition.

Several odd shaped foreign bodies placed at random within the skull could be accurately identified as to thier exact position by the most inexperienced member of the team, who incidently had no medical background.

A standard X-ray generator and tube was used in the majority of cases, however when a tube of spot size 0.3 millimeter, together with air-gap magnification (2.1:) was employed, better resolution resulted.

II. In order to determine if very small vessels could be visualized during angiography, experiments on 250 to 500 Gm rabbits were performed. These animals were anesthetized with 1 percent Sodium Nembutal injected via ear vein.

Several excellent quality angiographic studies were recorded using 2 cc. of 50 percent I-Iypaque injected transdiaphragmatically into the left ventricle. These studies proved to be the most remarkable laboratory studies performed. Contrast flow in vessels of 0.5 millimeter in diameter were recorded.

On a single radiograph, an angiocardiogram, aortic arch study, bilateral carotid and brachial angiograms, coeliac and mesenteric axis angiograms, nephroangiogram and intravenous pyelogram were all depicted as.

a brief three-dimensional phsiologic cine sequence. Also on the same picture the cardiac pulsations and diaphagmatic movements were present. Gas and bony densities did not obscure any detail. The renal calyses as shown on the I. V. P. gave exact relationships.

. Angiograms could be recorded in their entirety as a two-dimensional series if no rotation of the animal occured during the injection. This film would then be replayed on a viewer with the analyser interposed, allowing only one image to be observed by both eyes at the same instant. Twenty-four discrete images are recorded during each angiographic study.

III. Radiographs of moving joints (e.g., the hand and ankle) were also recorded as three-dimensional time sequence studies. These films readily displayed the movements of the carpal and matacarpal bones relative to each other.

IV. Three-dimension laminographic cuts were achieved by placing the area of interest as close to the axis of rotation as possible and rotating the subject through 20.'These studies can be achieved in from 1 to 8 seconds and as in the other studies, appear on a single piece of photographic material. The thick-cut" is approximately 2 to 3.0 cm. in thickness and can be viewed as the individual l0 discrete cuts which were necessary for the composite picture if the vieweranalyzer-grid is interposed.

The radiation to the patient is approximately three to four times the radiation necessary for a single standard exposure. When an angiographic sequence is recorded, the total radiation to the patient will be approximately 30 to 40 percent of the total radiation normally necessary.

Certain other embodiments of the instant invention should be noted. For example, there is a procedure of substraction" wherein when an angiogram is made of the skull a blood vessel may be superimposed with the bone of the skull and, therefore, would not show. Accordingly,'with present procedures, if another X-ray is made of the skull without the introduction of a dye, and

this picture is printed as a positive, it may be superimposed upon the negative angiogram of the skull thereby showing the hidden blood vessel. It can be readily seen that the instant invention could be used to make an angiogram of the skull without the need of the method of subtraction since all the blood vessels will show up in one or another of the cuts.

Various other procedures can be obviated by the practice of the instant invention as well as other expensive equipment. In the past multiple cuts have been made by means of a polytomographic machine. By using the apparatus andmethod of the instant invention the polytomographic machine is no longer needed. Additionally, it should be noted that three-dimensional laminography, an extremly important aspect of the instant invention has not been done before with prior art methods and apparatus. The present invention enables the practitioner, for the first time to perform threedimensional laminography. Furthermore, using certain prior art methods of obtaining a whole series of pictures, there was always a need to use a plurality of sheets of film as well as a rapid film changing device. By the practice of the present invention, these can be eliminated.

While the present invention has been discussed by reference to a preferred embodiment wherein an X-ray film is used to record the three-dimensional image, it should be understood that the film could be replaced with an image intensifier apparatus to record images which can all be integrated on video tape and replayed as a single cine or three-dimensional radiograph.

It should now be apparent that the objects initially set forth at the outset to this specification have been successfully achieved. Moreover, while there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,

What is claimed is:

1. Apparatus for use with sterographic radiography, or the like, comprising, in combination: a source of X- radiation; recording means responsive to said X- radiation for recording a radiographic image; a platform disposed between said source and said recording means for movably supporting a subject therebetween; displacement means for causing said platform to be displaced about an axis of rotation; movable shield means disposed between said source and the subject for permitting a predetermined amount of X-radiation emitted by said source to reach the subject; and control means cooperatively coupled to said source and to said shield means and to said recording means for synchronously enabling a sequence of exposures to be made during movement of said platform about said axis of rotation; said recording means including a cassette support and at least one replaceable cassette, said cassette comprising a first grid and a light-responsive film disposed adjacent said first grid, and means cooperative with said control means for causing relative displacement between said film and said grid, said first grid being formed with a plurality of X-ray permeable slots extending substantially parallel with respect to said axis of rotation, said cassette further including an image intensifying screen disposed adjacent said first grid, said first grid being disposed'between said film and said image intensifying screen, said image intensifying screen comprising fluorescent material capable of producing film-exposure radiation in response to unshielded X-radiation emitted by said source, thereby enabling a plurality of exposures of spaced portions of said film, said shield means including a shielding grid formed with a plurality of X-ray permeable slots extending substantially parallel with respect to the slots formed in said first grid. 7

2. Apparatus according to claim 1, wherein said cassette further comprises a second grid adjacent said film on the side thereof opposite from said first grid, said second grid being formed with a plurality of X-ray permeable slots extending substantially parallel with spect to said axis of rotation.

3. Apparatus according to claim 2, wherein said cassette comprises first and second image intensifying screens disposed adjacent said first and second grids, said first grid being disposed between said film and said first image intensifying screen, and said second grid being disposed between said film and said second image intensifying screen.

4. Apparatus according to claim 3, whereinsaid control means causes predetermined relative movement of said platform, said shield means, and said first grid, with respect to said film.

' 5. Apparatus according to claim 4, whereinsaid first and second grids are each generally opaque to said exposure radiation, said grids being fabricated of a sub-' stantially heavy metal foil formed with a plurality of parallel slots therein.

6. Apparatus according to claim 5, wherein said parallel slots are approximately 0.04 millimeter in width.

7. Apparatus according to claim 5, wherein said foil consists of a metal selected from thegroup consisting of gold, silver, platinum and lead.

8. Apparatus according to claim 5, wherein each of said slots has a width of 0.4/n millimeter, where n is an integer of a magnitude not to exceed 24.

9. Apparatus according to claim 8, wherein said movable shield means is formed with slots defined by side walls, said sidewalls diverging from top to bottom at an angle substantially equal to the normal spray of radia tion from said source.

10. Apparatus according to claim 4, further comprising means for vertical adjacent of said platform,

thereby regulating the location of said axis of rotation. s 

1. Apparatus for use with sterographic radiography, or the like, comprising, in combination: a source of X-radiation; recording means responsive to said X-radiation for recording a radiographic image; a platform disposed between said source and said recording means for movably supporting a subject therebetween; displacement means for causing said platform to be displaced about an axis of rotation; movable shield means disposed between said source and the subject for permitting a predetermined amount of X-rAdiation emitted by said source to reach the subject; and control means cooperatively coupled to said source and to said shield means and to said recording means for synchronously enabling a sequence of exposures to be made during movement of said platform about said axis of rotation; said recording means including a cassette support and at least one replaceable cassette, said cassette comprising a first grid and a light-responsive film disposed adjacent said first grid, and means cooperative with said control means for causing relative displacement between said film and said grid, said first grid being formed with a plurality of X-ray permeable slots extending substantially parallel with respect to said axis of rotation, said cassette further including an image intensifying screen disposed adjacent said first grid, said first grid being disposed between said film and said image intensifying screen, said image intensifying screen comprising fluorescent material capable of producing film-exposure radiation in response to unshielded X-radiation emitted by said source, thereby enabling a plurality of exposures of spaced portions of said film, said shield means including a shielding grid formed with a plurality of X-ray permeable slots extending substantially parallel with respect to the slots formed in said first grid.
 2. Apparatus according to claim 1, wherein said cassette further comprises a second grid adjacent said film on the side thereof opposite from said first grid, said second grid being formed with a plurality of X-ray permeable slots extending substantially parallel with respect to said axis of rotation.
 3. Apparatus according to claim 2, wherein said cassette comprises first and second image intensifying screens disposed adjacent said first and second grids, said first grid being disposed between said film and said first image intensifying screen, and said second grid being disposed between said film and said second image intensifying screen.
 4. Apparatus according to claim 3, wherein said control means causes predetermined relative movement of said platform, said shield means, and said first grid, with respect to said film.
 5. Apparatus according to claim 4, wherein said first and second grids are each generally opaque to said exposure radiation, said grids being fabricated of a substantially heavy metal foil formed with a plurality of parallel slots therein.
 6. Apparatus according to claim 5, wherein said parallel slots are approximately 0.04 millimeter in width.
 7. Apparatus according to claim 5, wherein said foil consists of a metal selected from the group consisting of gold, silver, platinum and lead.
 8. Apparatus according to claim 5, wherein each of said slots has a width of 0.4/n millimeter, where n is an integer of a magnitude not to exceed
 24. 9. Apparatus according to claim 8, wherein said movable shield means is formed with slots defined by sidewalls, said sidewalls diverging from top to bottom at an angle substantially equal to the normal spray of radiation from said source.
 10. Apparatus according to claim 4, further comprising means for vertical adjacent of said platform, thereby regulating the location of said axis of rotation. 